Small footprint technologies, such as the integrated fixed film activated sludge (IFAS) process, provide unique solutions for biological nutrient removal (BNR) facilities that face site constraints, expansion challenges, and/or the desire for a high quality effluent. The Yucaipa Valley Water District (YVWD) selected IFAS to expand the Henry N. Wochholz wastewater treatment plant (WWTP) capacity from 15140 m 3 /d (4 mgd) to 30280 m 3 /d (8 mgd) and to meet a total inorganic nitrogen (TIN) permit limit of 6 mg/L based on a 12-month average. The paper will discuss startup challenges with respect to the IFAS basins loading, media, aeration control as well as foaming issues. It will also provide information on current plant performance and operations.
A moving bed bioreactor (MBBR) pilot study was carried out to optimize design criteria and to evaluate four treatment strategies to design and operate the MBBR process to suppress nitrification while maintaining reliable carbonaceous BOD (CBOD) removal. The treatment objectives were to reliably control effluent NOx-N and soluble CBOD to less than 10 mg/L. The treatment strategies included: adjusting media loading rates, DO control, step-feeding of the process, and providing an internal recycle back to a switching (oxic/anoxic) zone to provide moderate nitrate removal if necessary. The pilot program results validated that the MBBR process could be designed and operated to accomplish reliable CBOD removal while adequately suppressing nitrification to consistently have an effluent nitrate concentration of less than 10 mg/L. The results were used to calibrate the GPS-X process simulation model to be used in design and to predict process performance under current and future loading conditions.
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